I've been using dgVoodoo to resize and improve the graphics of Sacred. I'm very pleased with the results, but I have a question: some parts of the interface and game world start appearing as these "boxes". I assume those are the sprites that are used to create the background, but these boxes only become visible when using forced Antialiasing. I tried to fiddle with different settings, but I was unable to get rid of them except by disabling MSAA. Is there any way to keep MSAA and not the boxing effect?

I've tried this. First if you want MSAA to work you need to stick to integer scales of the game's resolution. 1024x768,2048x1536,3072x2304, etc... Then it will work very nicely (for the most part, it will temporarily glitch out during zoom animation):

If you use the non-integer scale in your screenshot, which will also badly affect scrolling (if the entire background shimmering when you move, this is why), then your best choice is what I mentioned, post-processing AA. Here's ReShade's SMAA shader:

Could it be caused by the Windowed mode? Your screenshot seems to be fullscreen, however I'm trying to work with a window. I leave the game's config in Fullscreen mode, and I set dgVoodoo to force windowed.